added support for Obsidian style image references, including embedded dimensions

src/dragonglass/mparse.py

@@ -1,5 +1,6 @@
 #/usr/bin/env python3
 
+import re
 import markdown
 import xml.etree.ElementTree as etree
 from urllib.parse import urlparse
@@ -60,6 +61,98 @@ class MetaStripper(Extension):
         md.preprocessors.register(MetaStripper.MetaStripperProc(md), 'metastripper', PRIO_BASE)
 
 
+class ObsidianImages(Extension):
+    """An extension that supports image tags the way Obsidian handles them."""
+    DIMS = re.compile(r'(.*)\|(\d+)(?:x(\d+))?')
+
+    def __init__(self, context, **kwargs):
+        super(ObsidianImages, self).__init__(**kwargs)
+        self._context = context
+
+    @property
+    def invalid_reference_classname(self):
+        return 'invalid-reference'
+
+    def _parse_dimensions(self, s):
+        m = self.DIMS.match(s)
+        if m:
+            width = int(m.group(2))
+            height = int(m.group(3)) if m.group(3) else -1
+            return m.group(1), width, height
+        else:
+            return s, -1, -1
+
+    def _lookup_image_reference(self, name):
+        node, _ = self._context.src_index.lookup(name)
+        if node:
+            return node.link_target(self._context.url_prefix)
+        return None
+
+    class ObsidianImageProc(InlineProcessor):
+        def __init__(self, pattern, md, extref):
+            super(ObsidianImages.ObsidianImageProc, self).__init__(pattern, md)
+            self._extref = extref
+
+        def handleMatch(self, m, data):
+            name, width, height = self._extref._parse_dimensions(m.group(1))
+            link = self._extref._lookup_image_reference(name)
+            if link is None:
+                el = etree.Element('span')
+                el.set('class', self._extref.invalid_reference_classname)
+                el.text = name
+            else:
+                el = etree.Element('img')
+                el.set('src', link)
+                el.set('alt', name)
+                if width > 0:
+                    el.set('width', str(width))
+                if height > 0:
+                    el.set('height', str(height))
+            return el, m.start(0), m.end(0)
+
+    class GenericImageProc(InlineProcessor):
+        def __init__(self, pattern, md, extref):
+            super(ObsidianImages.GenericImageProc, self).__init__(pattern, md)
+            self._extref = extref
+
+        def handleMatch(self, m, data):
+            name, width, height = self._extref._parse_dimensions(m.group(1))
+            link = m.group(2)
+            if is_proper_url(link):
+                el = etree.Element('img')
+                el.set('src', link)
+                if len(name) > 0:
+                    el.set('alt', name)
+                if width > 0:
+                    el.set('width', str(width))
+                if height > 0:
+                    el.set('height', str(height))
+            else:
+                newlink = self._extref._lookup_image_reference(link)
+                if newlink:
+                    el = etree.Element('img')
+                    el.set('src', newlink)
+                    if len(name) > 0:
+                        el.set('alt', name)
+                    if width > 0:
+                        el.set('width', str(width))
+                    if height > 0:
+                        el.set('height', str(height))
+                else:
+                    el = etree.Element('span')
+                    el.set('class', self._extref.invalid_reference_classname)
+                    el.text = link
+            return el, m.start(0), m.end(0)
+
+    def extendMarkdown(self, md):
+        OBSIMAGE_PATTERN = r'!\[\[(.*?)\]\]'
+        GENERICIMAGE_PATTERN = r'!\[(.*?)\]\((.*?)\)'
+        md.inlinePatterns.register(ObsidianImages.ObsidianImageProc(OBSIMAGE_PATTERN, md, self),
+                                   'obsidian_images', PRIO_BASE + 1010)
+        md.inlinePatterns.register(ObsidianImages.GenericImageProc(GENERICIMAGE_PATTERN, md, self),
+                                   'obsidian_generic_images', PRIO_BASE + 1000)
+
+
 class ObsidianLinks(Extension):
     """
     An extension that processes Obsidian internal links in the [[page name]] format, as well as overrides the standard
@@ -151,4 +244,4 @@ class ObsidianInlines(Extension):
 
 
 def create_markdown_parser(context):
-    return markdown.Markdown(extensions=[MetaStripper(), ObsidianLinks(context), ObsidianInlines()])
+    return markdown.Markdown(extensions=[MetaStripper(), ObsidianImages(context), ObsidianLinks(context), ObsidianInlines()])